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Solaris ld raises reloc errors in JIT_WriteBarrier_Debug and ThePreStub #35154

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Solaris ld raises reloc errors in JIT_WriteBarrier_Debug and ThePreStub#35154
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area-VM-coreclros-SunOSSunOS, currently not officially supporteduntriagedNew issue has not been triaged by the area owner

Description

@am11
am11
opened on Apr 18, 2020

When linking libcoreclr.so, Solaris linker on SmartOS errors out as follow:

[vagrant@08-00-27-42-a0-69 ~/runtime]$ cd /home/vagrant/runtime/artifacts/obj/coreclr/SunOS.x64.Debug/src/dlls/mscoree/coreclr && /opt/tools/bin/cmake -E cmake_link_script CMakeFiles/coreclr.dir/link.txt --verbose=1

/opt/tools/bin/g++ -fPIC  -fstack-protector -g  -shared -Wl,-hlibcoreclr.so -o libcoreclr.so CMakeFiles/coreclr.dir/__/mscoree.cpp.o CMakeFiles/coreclr.dir/__/unixinterface.cpp.o CMakeFiles/coreclr.dir/__/__/__/__/version.c.o  ../../../utilcode/libutilcode.a ../../../debug/ee/wks/libcordbee_wks.a ../../../debug/debug-pal/libdebug-pal.a ../../../unwinder/libunwinder_wks.a ../../../vm/wks/libcee_wks.a ../../../binder/libv3binder.a ../../../md/compiler/libmdcompiler_wks.a ../../../md/runtime/libmdruntime_wks.a ../../../md/enc/libmdruntimerw_wks.a ../../../md/hotdata/libmdhotdata_full.a ../../../classlibnative/bcltype/libbcltype.a ../../../md/ceefilegen/libceefgen.a ../../../classlibnative/float/libcomfloat_wks.a ../../../inc/libcorguids.a ../../../gcinfo/libgcinfo.a ../../../debug/ildbsymlib/libildbsymlib.a ../../../utilcode/libutilcode.a ../../../binder/libv3binder.a ../../../libraries-native/liblibraries-native.a ../../../libraries-native/System.Globalization.Native/libSystem.Globalization.Native.a ../../../interop/libinterop.a ../../../pal/src/libcoreclrpal.a ../../mscorrc/libmscorrc.a ../../../palrt/libpalrt.a ../../../vm/eventing/eventpipe/libeventpipe.a ../../../pal/src/eventprovider/dummyprovider/libeventprovider.a ../../../nativeresources/libnativeresourcestring.a -lpthread -lrt 

Text relocation remains                 	referenced
    against symbol		    offset	in file
JIT_WriteBarrier_Debug              0x21      	../../../vm/wks/libcee_wks.a(jithelpers_fast.S.o)
ThePreStub                          0x15      	../../../vm/wks/libcee_wks.a(unixasmhelpers.S.o)
ld: fatal: relocations remain against allocatable but non-writable sections
collect2: error: ld returned 1 exit status

I have workaround this error by using -mimpure-text -Wl,-ztextoff linker flags.
Is this an indication of something that can be fixed in the highlighted stubs?

Activity

  1. Dotnet-GitSync-Bot
    added
    area-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
    untriagedNew issue has not been triaged by the area owner
    on Apr 18, 2020
  2. jkotas
    added
    area-VM-coreclr
    os-SunOSSunOS, currently not officially supported
    and removed
    area-CodeGen-coreclrCLR JIT compiler in src/coreclr/src/jit and related components such as SuperPMI
    on Apr 18, 2020

  3. jkotas commented on Apr 18, 2020

    @jkotas
    jkotas
    on Apr 18, 2020
    Member

    jmp C_FUNC(JIT_WriteBarrier_Debug) and jmp C_FUNC(ThePreStub) are obviously causing this problem.

    Try compiling extern void ThePreStub(); void Test() { ThePreStub(); } with gcc -fvisibility=hidden -O2 -S test.c and look at what the jmp looks like. The hand-written assembly should mimic that.

  4. am11 commented on Apr 18, 2020

    @am11
    am11
    on Apr 18, 2020
    MemberAuthor

    This is the output from SmartOS x64:

    $ echo "extern void ThePreStub(); void Test() { ThePreStub(); }" |\
     gcc -x c -fvisibility=hidden -O2 -S - -o- |\
     grep -B8 -A8 ThePreStub

.LFB0:
	pushq	%rbp
.LCFI0:
	xorl	%eax, %eax
	movq	%rsp, %rbp
.LCFI1:
	popq	%rbp
.LCFI2:
	jmp	ThePreStub
.LFE0:
	.size	Test, .-Test
	.section	.eh_frame,"a",@unwind
.Lframe1:
	.long	.LECIE1-.LSCIE1
.LSCIE1:
	.long	0
	.byte	0x1

    and on Ubuntu x64:

    	.p2align 4,,15
	.globl	Test
	.hidden	Test
	.type	Test, @function
Test:
.LFB0:
	.cfi_startproc
	xorl	%eax, %eax
	jmp	ThePreStub@PLT
	.cfi_endproc
.LFE0:
	.size	Test, .-Test
	.ident	"GCC: (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0"
	.section	.note.GNU-stack,"",@progbits

  5. jkotas commented on Apr 18, 2020

    @jkotas
    jkotas
    on Apr 18, 2020
    Member

    Hmm, this jmp ThePreStub looks exactly like the one in the asm code.

    Maybe you can try to add a call to ThePreStub in tailcall position somewhere in the C/C++ code and see whether it links fine?

  6. am11 commented on Apr 18, 2020

    @am11
    am11
    on Apr 18, 2020
    MemberAuthor

    With -fPIC, this compiles fine on SmartOS and Ubuntu:

    echo "int ThePreStub() {return 0;} int Test() { return ThePreStub(); } void Start() { Test(); }" \
    | gcc -x c -fvisibility=hidden -shared -O2 -fPIC -

    without -fPIC, it gives the same error on SmartOS but not on Ubuntu:

    Text relocation remains                         referenced
    against symbol                  offset      in file
.text (section)                     0x20        /var/tmp//ccFfambs.o
.text (section)                     0x38        /var/tmp//ccFfambs.o
.text (section)                     0x50        /var/tmp//ccFfambs.o
ld: fatal: relocations remain against allocatable but non-writable sections
collect2: error: ld returned 1 exit status

    and we are compiling coreclr with -fPIC on both SmartOS and Ubuntu, so should be fine.

  7. jkotas commented on Apr 18, 2020

    @jkotas
    jkotas
    on Apr 18, 2020
    Member

    What is the output of -S with -fPIC ? Is it different from the above?

  8. am11 commented on Apr 18, 2020

    @am11
    am11
    on Apr 18, 2020
    MemberAuthor

    It adds @PLT with -fPIC:

    --- without_fPIC
+++ with_fPIC
@@ -13,7 +13,7 @@
 .LCFI1:
        popq    %rbp
 .LCFI2:
-       jmp     ThePreStub
+       jmp     ThePreStub@PLT
 .LFE0:
        .size   Test, .-Test
        .section        .eh_frame,"a",@unwind
@@ -27,7 +27,7 @@
        .sleb128 -8
        .byte   0x10
        .uleb128 0x1
-       .byte   0x3
+       .byte   0x1b
        .byte   0xc
        .uleb128 0x7
        .uleb128 0x8
@@ -39,7 +39,7 @@
        .long   .LEFDE1-.LASFDE1
 .LASFDE1:
        .long   .LASFDE1-.Lframe1
-       .long   .LFB0
+       .long   .LFB0-.
        .long   .LFE0-.LFB0
        .uleb128 0
        .byte   0x4

  9. jkotas commented on Apr 18, 2020

    @jkotas
    jkotas
    on Apr 18, 2020
    Member

    Does the error go away if you replace jmp C_FUNC(ThePreStub) with jmp ThePreStub@PLT in unixasmhelpers.S ?

  10. am11 commented on Apr 19, 2020

    @am11
    am11
    on Apr 19, 2020
    MemberAuthor

    I had some other undefined symbols errors due to missing SunOS linker options for EXPORTS_FILE (-M for Illumos ld is similar as --version-file in GNU ld). Adding that linker options in few CMateLists.txt files automagically resolved this reloc issue. The build now succeeds on SmartOS without -mimpure-text option.

    Thanks for your help @jkotas.

  11. am11
    closed this as completedon Apr 19, 2020

  12. janvorli commented on Apr 20, 2020

    @janvorli
    janvorli
    on Apr 20, 2020
    Member

    @am11 the C_PLTFUNC macro is what you want to use instead of manually adding the @plt.

  13. am11 commented on Apr 20, 2020

    @am11
    am11
    on Apr 20, 2020
    MemberAuthor

    @janvorli, ack. I did not had to explicitly modify anything to fix this. It was implicitly fixed when I fixed other missing symbol issue; by adding some linker flags. PR has all the required changes: #35173.

  14. ghost locked as resolved and limited conversation to collaborators on Dec 9, 2020
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